One fuel injection system for internal combustion engines includes a fuel rail having filtered fuel under pressure entering it from a fuel tank. The fuel rail has fuel injectors connected thereto and the fuel injectors connect on the other end thereof to an intake manifold. A pressure regulator is connected between the fuel rail and the intake manifold to drain excess fuel in the fuel rail, through a fuel return line, back to the fuel tank when a differential pressure between the fuel rail and the intake manifold (i.e. the differential pressure across the fuel injectors,) is at a predetermined differential pressure. If the predetermined differential pressure is maintained, the internal combustion engine will function properly and if this predetermined differential pressure is not maintained, the engine will not function properly.
One prior art pressure regulator is disclosed in U.S. Pat. No. 4,327,767 to Fehrenbach et al. While this pressure regulator is adequate to do the aforementioned job, it is unduly complex, which causes reliability problems and also increases the manufacturing costs of the device.